1. Field of the Invention
The present invention relates to an apparatus for installing and retrieving hollow road signs installed on, for example, boundaries between road repairing sites and roadways.
2. Description of the Prior Art
Aiming at an improvement of safety, labor-saving and an improvement of working efficiency, an apparatus for automatically installing the above-described road signs on road surfaces has been proposed (for example Japanese Patent Application Laid-Open No. Sho 63-241208).
This apparatus for installing signs comprises conveyors provided swingably up and down and tiltedly on the side portions of a travelling vehicle body for conveying road signs, and wheels, which are trailedly rotated interlocking with a travelling of said travelling car body, provided on free end portions of conveyor frames, a rotating force of said wheels being transmitted to driving shafts of said conveyors through reduction gears to drive the conveyors at a speed proportional to a travelling speed of the travelling vehicle body, and said road signs carried on the conveyors being dropped one by one on said road surfaces at desired intervals with said travelling of the travelling vehicle body.
However, an inclinedly descending inertia force acts upon the road signs conveyed by means of the conveyors, so that disadvantages have occurred in that they are apt to fall forward when engaged with the road surfaces at one side end of a bottom portion thereof and they are apt to irregularly tumble in a standing posture, thereby shifting in position, when contacting the road surfaces at a corner portion of said bottom portion thereof.
In addition, the above described apparatus has aimed at merely the installation of the signs and thus they have been manually retrieved as before. That is to say, said improvement of safety and said labor-saving have not been sufficiently achieved and also said improvement of working efficiency has not been sufficiently achieved.
Furthermore, a disadvantage has occurred also in that when positions of the signs to be installed are changed on any one of the right side and the left side of the travelling vehicle body, positions of the apparatus for installing the signs to be mounted on brackets on both sides of a loading platform must be changed and thus not only hard labor is required and a danger is apt to occur but also plenty of time is taken.